Plans by the Government to overhaul lobbying laws are “seriously flawed” and should be delayed by up to half a year so that they can be improved, a cross party report concluded yesterday.

“Unnecessarily rushed” reforms had failed to address large sections of the lobbying industry, the Political and Constitutional Reform Committee said in an unflattering report.

The Government’s planned new laws on third-party political campaigning to prevent future lobbying scandals have been roundly criticised by MPs for being badly thought out and rushed, with one MP labelling them a “dog’s breakfast’.

Charities and pressure groups could have their websites shut down and their meetings cancelled if they were thought to be in breach of the proposed legislation, the Electoral Commission has warned, while adding the proposals could be an assault on free speech.

The Transparency of Lobbying, non-Party Campaigning, and Trade Union Administration Bill would set a £390,000 cap on the amount any organisation - excluding political parties - could spend across the UK during elections. A statutory register of lobbyists would also be set up, but only firms who declare their main business as lobbying would be included.

But the Political and Constitutional Reform Committee's report said: “As proposed, the Bill would do little, if anything, to impact upon the scandals that led to all parties supporting legislation. This will disappoint the public and reduce further their trust in politics.”

It added: “The Bill's definition of 'consultant lobbying' is flawed. Not only does it exclude in-house lobbyists, which was the Government's intention, but as currently drafted it would also exclude the vast majority of third-party lobbyists, and particularly the larger organisations.”

The report said the Bill, which will have a second reading in the Commons after MPs voted in favour of it earlier in the week, should not become law in its present form.